Textile drafting apparatus



Nov. 10, 1959 w. MACDONALD 2,911,685

TEXTILE DRAFTING APPARATUS Filed March 10, 1959 llll INVENTOR W41. TER MACDONALD Fig.4 BY g ATTORNEYS United States Patent TEXTILE DRAFTING APPARATUS Walter Macdonald, Seekonk, Mass.

A Application March 10, 1959, Serial No. 798,422

6 Claims. (Cl. 19-131) s This invention relates to textile drafting apparatus, and more particularly to improvements in means for supporting apron-tensioning rolls in spinning frames and similar machines employing drafting aprons.

The drafting of textile fibers ordinarily is accomplished by passing the strand of fibers through a series of pairs of rolls moving at progressively higher surface speeds. This results in attenuation of the strand, and at the same time, causes the component fibers to extend more nearly parallel to the axis of the strand itself. In such systems, drafting aprons frequently are employed as fiber control elements. Although a number of different structural arrangements have been proposed, nearly all of them require that the drafting apron be disposed so as to contact the fibers in the zone between two successive roll pairs and that the surface speed of the apron be the same as that of one of the roll pairs. For example, in a typical spinning frame installation, the drafting apron is looped about the lower middle roll and a nose bar located close to the lower front roll of the machine. In passing between the lower middle roll and the nose bar, the apron moves at the same speed as the lower middle roll and contacts the fibers to exert a control efliect thereon. In some instances, additional aprons or rolls are located so as to press the strand against the apron in the zone between the lower middle roll and the nose bar, but the specific arrangements vary somewhat in practice.

vIn order that the drafting apron may be tensioned properly, it is usual to pass the apron about a heavy tension roll located below the zone in which drafting takes :place; Such a roll rotates freely as the belt passes around it, and its weight applies the desired tensioning force'to the apron. Undesirable swinging movements of the tensioning roll are prevented by metal supporting arms pivotally mounted on the frame of the machine and having crooks or bends therein engaging trunnions on the ends of the tensioning roll.

After a period of use, the tension roll supporting arms become badly worn in the areas contacted by the rotating tension roll trunnions, and they no longer are complete effective in restraining the tensioning roll against undesired movement. When this occurs, the apron no longer runs smoothly, and the quality of the yarn is affected adversely.

Prior to the present invention, it was necessary to stop production operations for a prolonged period of time in order to repair worn tension roll supporting arms. The usual practice was to dismantle the machines to the extent required for the removal of the tension roll supporting arms, and then ship the worn support arms back to the factory for repair. Unless the mill kept an inventory of support arms for use as spare parts, it was necessary to keep the machines idle until the worn support arms were returned or replaced by new parts.

It is an object of this invention to overcome in a practical and inexpensive manner the objections and dis- 2,911,685 Patented Nov. 10, 1959 advantages experienced heretofore as a result of wear on tension roll supporting arms.

A more specific object of the invention is to provide a press-on bearing element which may be attached to a worn tension roll supporting arm easily and quickly without requiring the removal of the arm from the drafting machine.

Another object of the invention is to provide a press-on bearing element which may be applied to tension roll supporting arms to compensate for different degrees of wear and which will be held securely in place during the normal operation of the machine.

Yet another object of the invention is to improve the bearing relationship between an apron tensioning roll and the supporting arms therefor so that the drafting apron passing about the tension roll will run more smoothly.

The foregoing objects may be accomplished, according to one embodiment of the invention, by the provision of a plastic bearing element of a shape corresponding generally to that of the crook or bend of a tension roll supporting arm and having a groove in its outer surface for receiving the edge of the tension roll supporting arm in a force fit relationship, so that the bearing element may be securely attached to the crook of the supporting arm without requiring the use of fastening elements such as bolts or the like.

Since the shapes of the tension roll supporting arms produced by different manufacturers vary somewhat, it follows that the possible shapes of the bearing elements of this invention also vary. However, it may be stated that a typical bearing element in accordance with the present invention includes two straight portions connected together by a curved portion. The angle between the straight portions and the radius of the curved portion conform generally to the shape of the support arm with which the bearing element is to cooperate.

It is an important feature of the invention that the plastic bearing element may be used with tension roll supporting arms which have been subjected to dilferent degrees of wear. The straight portions of the bearing element contact straight portions of the inner edge of the supporting arm adjacent the curve or crook, so that ample contact is assured even though the actual crook or curve in the bearing arm may be disposed some distance away from the base of the groove in the bearing element if considerable wear has taken place. On the other hand, if the bearing element is used with a new or practically new support arm, the curved portion of the crook may bear directly against the base of the groove in the plastic bearing element.

Another feature of the construction is that the plastic bearing element is symmetrical about an axis extending through the center of the curved portion and about a plane passing through the center of the groove. This relationship makes it possible to use a bearing element with either a right-hand or a left-hand tension roll supporting arm. In other words, a single type of bearing element is all that is required for the repair of a complete spinning frame. q The material of which the plastic bearing element of this invention is constructed should have good bearing qualities in order that the tension roll trunnion contacted The use-ofthe plastic bearing element of this invention makes possible an impressive change in the nature of the operations involved in compensating for wear in tension roll supporting arms. It is no longer necessary to remove the supporting arms from the machine or to carry out expensive machining operations on the arms. Instead, the necessary repairs can be made in a few moments without removing the arms from the machine. All that need be done is to disengage the worn support arms from the trunnions of the tension rolls, press the plastic bearing elements into place, and then move the support arms back into engaging relationship with the tension roll trunnions. These simple operations can be carried out so quickly and easily that there is no longer any necessity for the prolonged shut-downs which have been commonplace heretofore.

Moreover, the use of the plastic bearing'element of this invention makes it possible for the tension roll to rotate with greater freedom. The trunnions on the tension roll bear against the smooth plastic surfaces of the element and rotate with minimum friction. As a result, the drafting apron runs more smoothly and the quality 'of the stock being drafted is improved.

A more complete understanding of the invention and its many advantages will be gained from a consideration of the following detailed description of an embodiment thereof illustrated in the drawings, in which:

Fig. 1 is an elevational view,'with certain parts shown in section, of a spinning frame embodying the invention;

Fig. 2 is a perspective view of a tension roll supporting arm having thereon a bearing element in accordance with the'invention;

Fig. 3 is a side elevational view of the bearing element;

Fig. 4 is a side elevational view of the tension roll supporting arm, illustrating the manner in which the bearing element cooperates with the edge of the arm and with a tension roll trunnion;

Fig. 5 is an end 'elevational view of the tension roll supportingarm with the bearing element in place thereon;

Fig. 6 is a detail cross sectional view taken along the line 6-6 in Fig. 4; and

Fig. 7 is an exploded view of the parts shown in Fig. 6.

The spinning frame illustrated in Fig. 1 is largely conventional. In the trade, such a machine ordinarily is referred to as a Shaw System frame. It includes a stationary support structure 2 upon which lower drafting rolls 4, 6 and 8 are rotatably mounted. These rolls are positively rotated at progressively higher speeds so that a strand of fibers passing downwardly through the machine will be attenuated in the required manner.

Top rolls 10 and 12, carried by a movable framework 14, are weighted so as to press downwardly against the rollers 4 and 8 and nip the strand portions in contact therewith. The mounting of the toprolls 10 and 12 and the means for biasing them toward the rollers 4 and 8 may vary somewhat, and it will be understood that the present invention is applicable to all of the various types of structures.

Adrafting apron 16 is looped about the lower middle roll 6, a stationary nose bar 18 located between the lower .rolls 6 and 8, and a heavy tensioning roll 20. Coacting with the upper surface of the drafting apron 16 is a large roll 22 which establishes a nip line in the zone of the middle roll 6 and which urges the strand against the surface of the apron 16 in the zone between the roll 6 and nose bar 18.

The apron tension roll 20 must be free to move in a direction having a downward component so that its weight may provide a tensioning force for the apron 16. However, the apron tension roll 20 must be restrained against oscillations or swinging movements which would .cause variations in apron tension. The necessary restraint is provided by tension roll supporting arms 24 supported on the frame 2 for pivotal movements by a shaft 26 and bearing against roll trunnions 28 at the ends of the apron tension roll 20. In accordance with the present invention, a plastic bearing element 30 is attached to the inner edge of each support arm 24 in position to contact the trunnions 28.

The support arm 24 shown in detail in Fig. 2 includes a generally U-shaped mounting portion 32 located at its rear end and having aligned openings 34 for the reception of the mounting shaft 26. Forwardly of the mounting portion 32, the main body 36 of the supporting arm 24 has an inner edge which includes straight portions 38 and 40 disposed at an acute angle to each other and connected together by a curved portion 42.

In a new support arm 24, the curvature of the portion 42 is regular so as to provide a smooth connection between the straight portions 38 and 40. However, as suggested in Fig. 4, wear will result if the arm 24 contacts the trunnion 28 directly, and the curvature of the portion 42 will change somewhat. In order to compensate for such wear, the repair part 30 of the present invention is attached to the arm 24.

The repair part or bearing member 30 is molded from some suitable plastic material such as nylon. It includes an inner edge having straight portions 44 and 46 connected together by a smoothly curved portion 48. The angle between the straight portions 44 and 46 of the inner edge of the plastic bearing member 30 is the same as the angle between the straight portions 38 and 40 on the inner edge of the main body 36 of the supporting arm 24 with which the bearing element is to cooperate in use. Also, the radius of curvature for the curved portion 48 is the same as that in a new support arm 24.

The outer edge of the bearing member 30 is provided with a groove 50, illustrated clearly in Fig. 7. This groove extends about the entire outer edge of the hearing member 30 for receiving therein the inner edge portions of the tension roll supporting arm 24. The groove 50 in the outer edge of the bearing member 30 must be formed with precision and its dimensions must be related carefully to the dimensions of the tension roll supporting arm 24 with which it is to cooperate.

The width of the groove 50 is slightly less than the thickness of the metal in the supporting arm 24. Fig. 7 illustrates this relationship in somewhat exaggerated'form. This relationship makes it possible for the parts to cooperate in a force fit, or interference fit, relationship to each other. Once the bearing member 30 has been pushed into place as shown in Fig. 6, the side walls of the groove 50 exert reliable gripping forces against the sides of the supporting arm 24 to hold the bearing element 30 securely in place. Consequently, there is no need for additional fastening'means of any kind.

Another significant characteristic of the groove 50 .in the outer edge of the bearing member 30 is that its base 52 is located at a uniform distance away from the straight portions 44 and 46 of the inner edge of the bearing element 30 at all points. That is to say, the base 52 of .the groove 50 is parallel to the straight portions of the inner edge of the bearing element 30. Therefore, when the bearing element 30 is applied to the supporting arm 24, the straight portions 38 and '40 of the inner edge of the supporting arm 24 may contact the base 52 of the groove 50 along substantial areas without distorting the bearing element materially. As a result, the inner edge portions 44 and 46 of the bearing element 30 will be .parellel to the portions 38 and 40 of the supporting .arm 24. e

The curved portion of the base 52 of the groove 50 has the same radius of curvature as the curved portion 48 .in the inner edge of the bearing element 30 and 783 the curved portion of a new support arm 24. In fact, the curved line designated 52 in Fig. 4 has the same shape and location as the curved inner edge of a new support arm.24.

u Referring to Fig. 4, however, it will be seen that the curved portion 42 of the inner edge'of the supporting a'rm24 need not contact the base 52 of the groove 50 in the bearing member 30. Fig. 4 shows a supporting 24 that has been in use for a substantial length of time, and the curved portion 42 of its inner surface shown in Fig. 4 is distorted somewhat due to wear. Such distortion is undesirable, and the bearing element 30 serves to compensate for it. The angular'disposition of the end portions of the bearing element 30 makes it possible to fix the bearing element in position on the support arm 24, even though there may be a substantial space between the curvedv portion 42 of the inner edge of the roll supporting arm 24 and the base 52 of the groove 50 in the bearing element 30.

It is pointed out also that the trunnion 28 on the apron-tensioning roll 20 cooperates with the bearing member 30 in such a way as to keep the bearing element 30 in position on the supporting arm 24. Two factors contribute to this result. One is the direct holding pressure between the trunnion 28 and the bearing element 30. Another is that the frictional drag, produced by rotation of the trunnion 28, tends to twist the bearing element 30 in such a manner that the bearing element 30 actually moves into firmer engagement with the straight portion 38 of the inner edge of the supporting arm 24.

The supporting arm 24 illustrated in the drawings is a right-hand supporting arm. It cooperates with the right-hand trunnion on the apron tension roll 20. At the other end of the apron tension roll 20, there is a similar supporting arm, the U-shaped mounting portion of which is the reverse of the mounting portion 32 shown in Fig. 2. It will be evident that a single bearing member 30 constructed as shown in the drawings may be applied to either one of the supporting arms. This versatility simplifies the problem of stocking suitable re pair parts. This is possible because the bearing member 30 is symmetrical about an axis bisecting the angle between the straight portions 44 and 46 of its inner edge and also symmetrical about a plane passing through the center of the base 52 of the groove 50.

The desirable characteristics for the plastic material from which the bearing member 30 is molded should now be evident. The inner edge of the plastic bearing member 30 should present a minimum of frictional resistance to rotation of the trunnion 28 to be engaged thereby. Also, the material must be resilient so that an interference fit may be established between the walls of the groove 50 in its outer edge and the metal supporting arm 24, and the material must be stiff enough to remain in firm holding engagement with the sides of the supporting arm 24 when the apparatus is in use. Nylon and delrin have been found to be suitable materials, and other plastics having the required characteristics may be used, if desired.

It has been indicated above that the plastic bearing member 30 is a repair part. It may be used to great economic advantage in correcting for wear on the curved portion 42 of the inner edge of a tension roll supporting arm 24. However, the bearing element 30 also is useful in connection with new supporting arms 24. When applied to a new arm, the bearing element 30 serves to prevent undesirable wear and it also enables the trunnion 28 to rotate more smoothly and evenly.

A typical repair operation utilizing the present invention is a simple one indeed. When a supporting arm 24 has become worn, the difliculty may be corrected by simply disengaging the arm 24 from the adjacent trunnion 28 and pressing a palstic bearing element 30 into place on the inner edge of the supporting arm 24. The arm 24 then may be brought back into position with respect to the trunnion 28 to complete the job.

Although a single embodiment of the invention has been illustrated and described in detail, modifications and variations thereof will be apparent to persons skilled in the art. It is intended therefore that the foregoing" description should be considered as exemplary only, and that the scope of the invention should be ascertained from the following claims.

Iclaim: 1. In a textile drafting machine of the type having endless drafting apron, 5 an apron tension roll disposed within said apron, trunnions -on the ends of the tension roll, and'tension roll support 'arms for restraining the tension roll against swinging movement, each of the support arms havingan inner edge for contacting the tension roll trunnion adjacent thereto, the improvement which comprises press-on plastic bearing members each having a groove in its outer edge receiving the: inner edge of a tension roll support arm in a force fit relationship therewith and an inner edge bearing against a tension roll trunnion.

2. In a textile drafting machine of the type having an endless drafting apron, an apron tension roll disposed within said apron, trunnions on the ends of the tension roll, and tension roll support arms for restraining the tension roll against swinging movements, each of the support arms having an inner edge for contacting the tension roll trunnion adjacent thereto, the improvement which comprises press-on nylon bearing members each having a groove in its outer edge receiving the inner edge of a tension roll support arm in a force fit relationship therewith and a smooth inner edge bearing against a tension roll trunnion.

3. In a textile drafting machine of the type having an endless drafting apron, an apron tension roll disposed within said apron, trunnions on the ends of the tension roll, and tension roll support arms for restraining the tension roll against swinging movements, each of the support arms having an inner edge including two straight portions extending at an angle to each other and being connected together by a curved portion for contacting the tension roll trunnion adjacent thereto, the improvement which comprises a plastic bearingmember on each of said tension roll support arms, each of said plastic bearing members having an inner edge including two straight portions extending at an angle to each other and being connected together by a curved portion, the angle between said straight portions of said bearing member being the same as the angle between said straight portions of the support arm, said bearing member having a groove. in its outer edge receiving the inner edge of a tension roll support arm in a force fit relationship therewith.

4. In a textile drafting machine of the type having an endless drafting apron, an apron tension roll disposed within said apron, trunnions on the ends of the tension roll, and tension roll support arms for restraining the tension roll against swinging movements, each of the support arms having an inner edge including two straight portions extending at an angle to each other and being connected together by a curved portion for contacting the tension roll trunnion adjacent thereto, the improvement which comprises a plastic bearing member on each of said tension roll support arms, each of said plastic bearing members having an inner edge including two straight portions extending at an angle to each other and being connected together by a curved portion, the angle between said straight portions of said bearing member being the same as the angle between said straight portions of the support arm, said bearing member having a groove in its outer edge receiving the inner edge of a tension roll support arm in a force fit relationship therewith, and said groove including a base extending parallel to the straight portions of the inner edge of said bearing memher.

5. A press-on repair part adapted to be attached to the roll-contacting portion of a tension roll support arm in a textile drafting machine of the apron type to compensate for wear, said repair part comprising a plastic bearing member having an inner edge including two straight portions connected together by a curved portion and having a groove in its outer edge for receiving the inner edge "of the support arm in a force fit relationship therewith,'the base of said groove in the zones opposite said straight portions of said inner edge being straight and parallel to said straight portions of; said inner edge.

6. A press-on repair part adapted to be attached'tojthe roll-contacting portion of a tension roll support arm in a textile draftingmachine of the apron type to corn-pensate for wear, said repair part comprising a plastic bearing member having an inner edge including two straight port'ions connected together by a curved portion and having a groove in its outer edge for receiving'the inner edged the support arm in a force fit relationship therewith,.the

base of said groove in the zones opposite said straight 15 portions of said inner edge beingstraight andparallelto said straight portions or said inner edge,vsa'id' bearing. member being symmetrical about both' an axis bisecting' the angle between said straight portions and aplan'e passing through the middle of said groove so that it maybe applied to both right-hand andleft-hand support arms. References Cited inthefile of this patent UNITED STATES PATENTS v Cotchett et al. Aug. 19, 1952 2,657,434- Tarbox et a1 Nov. 3, 1953 2,689,098 Shacklett et a1. -4. Sept. 14, 1954' 238934165. Noguera July 7, 1959' 

